This application claims priority under 35 U.S.C. 119 from United Kingdom Application Serial No. 0026027.3, filed Oct. 24, 2000, which application is made a part hereof by reference.
The present invention relates to an extractor for bearings, bushings, sleeves, liners, and the like.
Many methods of extracting bearings, bushings, sleeves, liners and the like (hereinafter referred to generally as bushings) which are an interference fit in a housing often result in damage to the bushing and/or the housing.
Using a simple drift to drive out the bushing will score the housing and deform the end of the bushing. It also requires access to both ends of the housing.
Various pulling methods have been proposed.
U.S. Pat. No. 4,214,362 and U.S. Pat. No. 4,369,569 describe a tube puller in which an extractor cam forces gripping surfaces against the bushing inside wall, damaging the bushing and also risking distortion of the housing wall.
U.S. Pat. No. 5,249,342 describes an extractor which can be operated from one end of the housing. A cam is inserted through the bushing, followed by a collet. The collet has a number of legs and these are urged outwards by the cam to a predetermined diameter as the cam is withdrawn. Lips on the legs engage the distal end of the bushing so that the cam, collet and bushing are withdrawn together. Accurate sizing of the collet and cam ensure that there is no distortion of the bushing and no scoring of the housing surface, avoiding any need to repair or dress the housing, and allowing re-use of the bushing when appropriate. However, the collets are expensive to manufacture, and the collet/cam assembly must be tailored to a particular bushing internal diameter.
A first aspect of the present invention provides an engaging device for engaging an end of a bushing prior to extraction of the collet and bushing from a housing, the device comprising a plurality of engaging elements each having a laterally extending lip thereon, and means for releasably connecting the elements together.
Preferably, the connected elements form a chain which is flexible to allow the chain to be rolled up for insertion in a bushing, and unrolled to place the elements against the bushing inner surface. In use, the engaging elements are arranged inside the bushing, with the lips extending behind the bushing end surface. An extractor then applies a removal force to the engaging elements to force the elements and bushing from the housing.
By releasably connecting the engaging elements together, the number of elements can be varied to suit the diameter of the bushing being extracted. The elements may be clipped together, preferably by clips which each engage two adjacent elements, forming a chain or bandolier.
To remove a bushing, a chain of elements is formed into a spiral or otherwise collapsed and inserted into the bushing. The spiral is expanded out to a broken loop or circle to engage the lips of the engaging elements behind the distal end of the bushing. An extraction tool can then bear on the ends of the elements to pull the elements and bushing from the housing.
A former can be passed into the ring of engaging elements to urge them against the bushing, ensuring that the lips sit snugly on the end of the bushing as the elements are extracted with the bushing.
When the extraction is made from one end only of the housing, the extraction tool may be fed through the bushing before the engaging elements are put in place, or it may be provided with a collapsible claw which can be opened out after it has been fed through the elements and the former.
Thus, the invention provides a system which can be adapted to fit a wide range of bushing diameters by changing the number of engaging elements and/or the spacing between the elements. Engaging elements of different size may also be provided, smaller sizes being more suited to extracting smaller diameter bushings.
The lip on an engaging element is sized to bear on the end of the bushing and carry the force of the extraction tool to the bushing. The lip is dimensioned to stop short of the housing surface to avoid any scarring of the surface. Preferably the lip is formed at an end of the engaging element, the body of the element extending within the bushing.